K75c Coolant Leak

[ROBFRITZ]

While riding the 1986 K75C in stop and go traffic, on a 100 degree day, the engine temperture light came on. Next coolant started to spray out of the overflow vent cap. This only happens when it is very hot and in traffic. I was advised to replace the radiator cap and keep an eye on the cooling system. Any other recomendations? Thanks.

[Ted]

If you are near a dealer, I would have them test the cap before replacing it. It takes about 30-seconds. You might want to replace the gaskets in there, they like to go bad with age. Also, make sure your coolant is no more than two years old. Changing it is easy, personally I prefer the BMW purple stuff and gladly eat the $8 or so premium for the peace of mind (and no forgetting that the coolant drain plug crush washer is copper.) Your manual will have the correct mix of distilled water to coolant, I seem to remember it is 55% distilled water, 45% coolant but don't quote me on that.

Here is the schema from Max BMW's online parts fiche (http://www.maxbmwmotorcycles.com/fiche/fiche.asp):
http://www.maxbmwmotorcycles.com/fiche/DiagramsMid/B0003087.png

[breyfogle]

While riding the 1986 K75C in stop and go traffic, on a 100 degree day, the engine temperture light came on. <snip> Any other recomendations? Thanks.

Did the fan come on ? K75's so rarely need their fan that it is a rather common problem for the fan motor shaft to seize without the owner knowing about it. Then, just when you really do need the fan on that 100 degree stop & go day, ==> over-heat !!

[98lee]

While checking/replacing the radiator cap, carefully check the overflow hose (part #11 in the diagram above) for cracks (usually near the hose clamps). If ANY cracks, replace it.

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